The invention relates to solar collectors of the type in which a flat plate absorber member collects heat from the sun and transfers it to a fluid which is flowing in heat exchange relation with the absorber member. Conventionally, the absorber member is a copper sheet of substantial thickness to which a series of liquid carrying tubes is soldered. The absorber member is generally painted black and mounted on an insulating surface such as wood or foam which is in turn mounted in a collector frame tightly covered with one or two panels of glass. The glass helps prevent re-radiation of energy to the atmosphere and reduces losses by conduction and convection. Although such collectors are very simple, they are quite heavy and expensive due to the large amount of copper sheet and tubing they require. In view of the large amount of collector surface required in a typical solar heating installation, the expense of the installation has seldom been justified where alternate sources of energy have been available.